function* start(){
  //next()执行到yield 并把yield后面的值返回，第二次next(),'var a =' 开始执行,next(args)的参数会作为上次yield的值赋给a
  var a = yield 'start';
  console.log(a);
  var b = yield 'running';
  console.log(b);
  var c = yield 'end';
  console.log(c);
  return 'over';
}

// console.log(start.constructor.name); //GeneratorFunction

module.exports = start;
